Nowadays, there are several devices for taking samples of soft tissue, these devices being generally used to extract, in a minimally invasive way, a sample of an organ from a human being or an animal for analysis purpose. This extraction operation is generally known as biopsy and the device used is known as a biopsy gun.
Such a sampling device comprises in particular a sampling needle formed by a cannula and a stylet, an arming mechanism placed on a body and a trigger also placed on the body of the device.
The arming mechanism is used to partially retract the needle towards the inside of the body of the device. The device is placed near the organ from which a sample is to be taken, and then the trigger is pressed so that the needle can penetrate into the organ. The needle being formed by a stylet and by a cannula, the stylet penetrates into the organ, then the cannula covers the stylet. The stylet comprises at least one notch receiving the tissue sample to be taken. When the cannula covers the stylet, the tissue sample is trapped in the notch and is cut. The unit is withdrawn so that the sample(s) arranged between the stylet and the cannula can be removed. An example of application of such a device is taking tissue samples from the prostate.
The arming of the needle is generally achieved in two steps, namely the arming of the cannula in a first step and the arming of the stylet in a second step.
During sampling of tissues, it is common for the person carrying out the sampling to have only one free hand, while the other hand is being used to hold other medical devices, such as for example an echographic probe. In this case, it is important to be able to manipulate the sampling device with one single hand. Here, the handling includes the arming of the cannula, the arming of the stylet and the release of the shot allowing the sample to be taken.
An example of existing devices which enable handling with one single hand is described in the U.S. Pat. No. 7,153,275. This device is perfectly functional if handled correctly as in most cases. However, incorrect handling may cause problems. In particular, when the arming of the cannula or the stylet has not been achieved correctly, the shot can be unintentionally released. In particular, this can cause problems if a shot is released before the device is correctly placed near the organ from which a sample is to be taken.
Another problem known with this kind of device is that incorrect handling of the arming mechanism may cause the shooting mechanism to become totally jammed, thus rendering the device unusable.
The following description describes a tissue sampling device which has the advantages of the devices of the prior art i.e. it is possible to use this device with one hand. However, this device does not have the drawbacks of the systems of the prior art. Thus, even in the case of incorrect handling, the shot is not released unintentionally. Moreover, the device cannot be jammed as a result of incorrect handling.